:Actually snprintf and some other functions in the same league have a
:fundamentally wrong return type. They should return size_t or ssize_t,
:because sizeof(size_t) >= sizeof(int) and the number of bytes actually
:writeable e.g. to a string is limited by (s)size_t. Yes, I consider this
:a flaw in the standard.
:
I think snprintf got it right, and things like read() and write()
got it wrong. Just because you have a 64 bit address space
doesn't mean that it makes sense to support it for everything,
much less a string operation that 99.99999999999999% of the
uses in code use values far less then 2^31. 'int' is a lot easier
to understand both for sizeof() and as the return value to a read or
write, and having sizeof() return unsigned has tripped me up more
times then I can count because 99% of the time I am comparing it
against int's, not unsigned ints. Plus I use negative numbers all
the time to mean special things, and size_t screws that all up
to the point where it is a royal pain in the ass. Just because
sizeof() can only return an unsigned value doesn't mean that it
should be typed that way.
It becomes absurd after a while but that hasn't stopped the
standards folks from doing it anyway.
-Matt
Matthew Dillon
<dillon@backplane.com>
:...
: if (read(0, buf, sizeof(buf)) != sizeof(buf)) {
: ...
: }
:generates a warning, because to allow error validation read returns
:a signed size_t, but sizeof is unsigned.
:
:To summarize this whole discussion, it can't be avoided to add casts,
:but it is important to understand when casts are necessary and how
:to correctly cast. For example, it is better to cast the sizeof(buf)
:to ssize_t in the example above, because _we_ know that there won't be
:any problem. It would be nice if GCC could automatically stop printing
:warnings if a fixed integer can be representated as both or an unsigned
:integer of a smaller type is compared to a greater signed type. The first
:can be savely promoted to signed and the latter as well.
:
:Joerg